Victoreen Model 300 "Proteximeter"

Victoreen Model 300 "Proteximeter"

The Proteximeter(Model 300) is a portable beta-gamma condenser ion chamber (similar in operation to a pocket chamber) that records an integrated exposure up to 200 mR on a single scale. This range was chosen so that the “daily tolerance dose” of 100mR would register a reading in the middle of the scale. The operating instructions are located on the bottom of the case (3.5" x 9" x 4.5") so that they can't be lost.

Victoreen Model 300 "Proteximeter"
Victoreen Model 300 "Proteximeter"

The polyethylene chamber (see diagram to right), which is electrically connected to the grid of a V124B electrometer tube, is charged by a battery from which it is then disconnected. The charging is accomplished by turning the instrument upside down. Any subsequent ionization in the chamber due to radiation reduces the chamber’s charge and that on the electrometer tube grid. The resulting increase in the current across the tube is measured by a microameter and this current is used as an indication of the accumulated exposure.

Victoreen Model 300 "Proteximeter"

The Proteximeter was developed by the Victoreen Instrument Company during WWII-the company Model Series Index’s assigned date for the Proteximeter is February 1945. In Health Physics: A Backward Glance (1980), Dale Trout described how he used the Proteximeter towards the end of WWII for the measurement of radiation levels around radiography units such as those used for X-raying shell casings. During the atomic tests Able, Baker and Charlie in the Pacific following WWII (1945 and 1946), the Proteximeter was one of the primary instruments employed for the purpose of radiation safety. Almost all of the instruments used at these tests were provided by the Victoreen Company.The example shown above is probably a fairly early version because it is labeled as "PRODUCTION SAMPLE - NOT TO BE SOLD, Return to Lab. Director, Tested and Appr'd."

Donated by Victoreen Instrument Company courtesy of John Pobicki.


  • Dale Troutin “Health Physics: A Backward Glance”ed. Kathren, R.L. and Ziemer, P.L., Pergamon Press, New York, 1980.
  • Victoreen Model Series Index, assigned date February 1945.
  • AEC Radiation Instrument Catalog, page date July 1, 1950.
  • Advertisements and product descriptions: Nucleonics October 1947, p 83; Nucleonics December 1950 back cover.
  • Davis, D.M. Health Physics Division Instrument Manual, ORNL-332, June 1949, p.65.
  • Davis, D.M., Gupton, E.D. and Hart, J.C. Applied Health Physics Radiation Survey Instrumentation, ORNL-332 (1st Rev.), January 1954.
  • Campbell, D.C. Radiological Defense,Vol. IV, Armed Forces Special Weapons Project, 1950.